Glaucoma is a condition of the eye in which a build-up of pressure inside the eye causes degenerative changes that damage the retina and optic nerve, therefore resulting in blindness.

Your eye needs a certain amount of pressure to keep the eyeball in shape so that it can work properly. In some people, the damage is cause by raised eye pressure. Others may have an eye pressure within normal limits but damage occurs because there is a weakness in the optic nerve. In most cases both factors are involved but to a varying extent.

Eye pressure is largely independent of blood pressure, and is in fact controlled by a layer of cells behind the iris (the coloured part of the eye). These cells produce a watery fluid, called aqueous, which passes through a hole in the centre of the iris (called the pupil) to leave the eye through tiny drainage channels. These are in the angle between the front of the eye (the cornea) and the iris and return the fluid to the blood stream. Normally the fluid produced is balanced by the fluid draining out, but if it cannot escape, or too much is produced, then your eye pressure will rise. Note that the aqueous fluid has nothing to do with tears!

Glaucoma is an optic neuropathy which is characterized by a specific pattern of optic nerve head and visual field damage. In some cases, the damage may be attributed to the increased intra-ocular pressure. However, in other instances, the underlying basis for the continuous damage to the optic nerve is not clear. Glaucoma is the second leading cause of legal blindness. It causes blindness in nearly 12,000 americans annually.

Two main categories of glaucoma:

• Open-angle glaucoma: the most common form of glaucoma.
• Closed-angle glaucoma: a less common and more urgent form of glaucoma.

The most common form of glaucoma is called open-angle glaucoma. It is so named because the angle from which the fluid drains out of the anterior chamber is open. This form of glaucoma affects approximately 3 million Americans. Glaucoma occurs in nearly 1 to 2 percent of people over the age of 40.

Another rare form of glaucoma is the closed-angle glaucoma wherein the person suffers from damage to the optic nerve and this in turn causes loss of vision although there is no blockage of the eye canals and no build up of pressure. There isn’t too much information on closed-angle glaucoma but a general consensus shows that it is caused due to unusually delicate optic nerve or it can be inherited.

Eye drops are the most common form of treatment for glaucoma. There are several different types and you will be prescribed the one most suited to you. The drops are designed to reduce the pressure in your eye. They do this either by reducing the amount of fluid your eye produces, or by increasing the amount of fluid which drains from your eye.

If eyedrops aren’t working, there are several surgical techniques available to relieve eye pressure. One common surgery is the trabeculectomy, where an alternate drainage pathway is surgically created. A small hole is cut through the superior limbus, creating a drainage tract from the anterior chamber to a space under the conjunctiva. This can be very effective in decreasing pressure, but if the patient is a rapid healer the shunt can scar down and close, so anti-metabolites like mitomycin-C are often applied to the site. If this surgery doesn’t work, a plastic tube-shunt can be inserted into the anterior chamber that drains to a plate fixed under the conjunctiva further back.

When pressure can not be lowered adequately or side effects are too severe, eye doctors turn to laser treatment as the next, and necessary, treatment. Laser surgery uses focused light to reopen the drainage area to alleviate the buildup of fluid. After receiving a numbing agent in the eyes, patients sit facing the laser machine, while the eye care professional gently holds a lens used to aim the laser beam to the eye. A beam of light hits the eye’s lens and reflects into the drainage area of the eye. The entire procedure usually takes only minutes.

It’s up to you to protect your eyes from glaucoma. Take these steps:
* Have eye exams as often as your eye doctor suggests.
* If you have glaucoma, use medicine as prescribed. Call your doctor if you have questions or problems.